Charlton Galvarino wrote:
Hi, Frank.
I believe much of the performance problem is that some versions of
GDALOpen() do a scan of the whole directory as part of the file opening
process. In a directory, like Steven's, with 60000 tiles (120000 files!)
that becomes a significant performance problem. I have suggested a
configuration item that might disable this depending on his version of
GDAL.
That got my attention!
In one dir say I have 20k .png images. In that same dir I have 400 .shp
tileindexes which point to them. I.e. each tileindex points to 50 of those
.png's. Are you saying that when I send a MS viz request based on a
specific tileindex .shp, I could be scanning the whole dir (depending on my
version of gdal)?
Charlton,
Yes, for each GDALOpen() request. So for each actual raster file which we
attempt to open.
I would add some other aspects of operating systems may respond poorly to
very large directories so it is a common practice to break down tiling
systems into a heirarchy (like the google tile tree).
I'm not saying your configuration can't be fast, but you are playing with
fire if performance is the goal.
Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, warmer...@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent
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